a The increase in miles not reported can be attributed to the fact
that many states are electing to report pavement conditions by the more objective
International Roughness Indicator (IRI) rather than by the Present Serviceability
Rating (PSR), which has traditionally been used to determine pavement conditions
for these systems.

b Included in row below.

NOTES

Because of the transition to a new indicator for pavement condition beginning
with U.S. Department of Transportation, Federal Highway Administration (FHWA)
data published in 1993, comparisons between pre-1993 data and 1993 and later
data are difficult. Thus, trend comparisons should be made with care. For additional
information, the reader is referred to the accuracy profile for this table in
the appendix. Total mileage in this table will not match that in table 1-5 because
of a change in the method of creating mileage-based tables derived from the
Highway Performance Monitoring System, beginning with the 1997 issue of FHWA's
Highway Statistics